The United States Constitution can be changed informally. Informal amendments mean that the Constitution does not specifically list these processes as forms of amending the Constitution, but because of change in society or judicial review changed the rule of law de facto.
A) he negotiated a clear border between Spain & France.
B) he stopped the Muslim advance from Spain into France.
C) he welcomed ambassadors and scholars from Moorish Spain.
D) he established a Christian kingdom in a corner of northern Spain.
Immigration would be the best option